Solenoids are frequently used to inject fuel into automotive engines, to control electronic transmissions, and sometimes to actuate brakes on a vehicle. All such solenoids use a solenoid driver that causes current to be injected into the solenoid's coil at preselected times and at preselected levels in order to control the position of the solenoid's armature.
One of the drawbacks of conventional solenoid drivers is that they consume an undesirably high level of power when they are causing a solenoid to close (i.e., when the solenoid's armature is being seated). This high power consumption is particularly evident in solenoid drivers that are designed to rapidly close a solenoid, such as the solenoid in a fuel injector.
Not only is the high level of power consumption wasteful, but it also requires relatively expensive output transistors that are capable of safely dissipating such power. Some applications also require that the output transistors be mounted on a heat sink, thus further increasing the cost of the solenoid driver.